javascript
<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title> ?
? <script type="text/javascript">
? ?function count(){
? ? var txt1 ? = parseInt( document.getElementById('txt1').value);//鑾峰彇絎竴涓緭鍏ユ鐨勫€?
var txt2 ? = parseInt( document.getElementById('txt2').value);//鑾峰彇絎簩涓緭鍏ユ鐨勫€?
var select = document.getElementById('select').value;//鑾峰彇閫夋嫨妗嗙殑鍊?
var result = '';
switch (select)
{
case '+':
result = txt1 + txt2;
break;
case '-':
result = txt1 - txt2;
break;
case '*':
result = txt1 * txt2;
break;
case '/':
result = txt1 / txt2;
break; ?
}
? ? ? ? ?document.getElementById('fruit').value = result;//璁劇疆緇撴灉杈撳叆妗嗙殑鍊?
? ?}
? </script>?
?</head>?
?<body>
? ?<input type='text' id='txt1' />?
? ?<select id='select'>
<option value='+'>+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
? ?</select>
? ?<input type='text' id='txt2' />?
? ?<input type='button' value=' ?= ?' ?onclick = "count()" />?
? ?<input type='text' id='fruit' /> ??
?</body>
</html>
document.getElementById('fruit').value = result;這句話起到什么作用？
2016-03-29
計(jì)算的結(jié)果呀也必須賦值的，
2016-03-29
把result的值賦值給輸出框